A major mission of this group involves the basic research and service functions of NMR instrumentation provided to NIDDK scientists of the Laboratory of Bioorganic Chemistry, Laboratory of Medicinal Chemistry, other NIH laboratories and, to a limited extent, to scientists of other institutes. Assistance in the solution to structural problems is rendered on request. Provide critical interaction as well as extensive collaboration with other scientists in this Institute. In the past year, we made a major upgrade of a 15 years old console with a new state-of-the-art console and a cryo-probe for our 500 MHz NMR spectrometer. We also purchased a new 600 MHz spectrometer. Two collaborative projects that need the highest possible field strength and sensitivity shall benefit from the addition of these two high field instruments. These include structural elucidation of biologically active substances isolated from natural sources (in collaboration with Dr. John Daly's group) and conformational studies of structurally altered DNAs resulting from chemical modification by diolepoxides metabolically formed from known chemical carcinogens, such as benzo[a]pyrene (BaP) (in collaboration with Dr. Donald Jerina's group). It is hoped that the information obtained in the latter study shall shed some light on the